The present invention relates to an image data processing device such as an MFP (Multi Function Peripheral) and an image data processing program capable of processing, for example, encrypted PDF (Portable Document Format) files.
A general image data processing device such as an MFP is configured to obtain image data by reading (scanning) a document, and to convert the image data into an encrypted PDF file. Such an encrypted PDF can be attached to an electronic mail, stored in an external storage device connected to the MFP via an USB port, or transferred to a server connected to the MFP via network.
For example, Japanese Laid-open Patent Publication No. 2005-277736 discloses a system that creates an encrypted PDF file by encrypting scanned image data.
In the conventional system, when the MFP (i.e., the image data processing device) creates the encrypted PDF file, the MFP needs to have a public key of a requester (who requests to create the encrypted PDF file).
For example, when the MFP decrypts the PDF file having been encrypted using the public key, the MFP needs to obtain a secret key (corresponding to the public key) from another device via network. Therefore, if a communication error occurs between the MFP and the device having the secret key, security may not be ensured.
Therefore, it is demanded to enhance security in processing encrypted data (for example, an encrypted PDF file).